The present disclosure relates generally to a method and system for monitoring physiological parameters of a patient. Specifically, embodiments of the present invention relate to more accurate estimation of intravascular blood volume and fluid responsiveness by adjusting pulse oximetry waveform measurements to account for variations in respiratory parameters and/or other patient parameters.
This section is intended to introduce the reader to aspects of the art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring many such characteristics of a patient. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine.
One physiological parameter that physicians may wish to monitor is blood fluid volume (i.e., intravascular volume). Variations from normal fluid volume in the blood may indicate a change in clinical condition or an injury. For example, hypovolemia is a state of decreased intravascular volume that may be associated with dehydration. Correct clinical assessment of hypovolemia is complex. More specifically, intravascular volume is difficult to estimate, particularly in critically ill patients. Without an accurate assessment of a patient's intravascular volume, it is difficult to predict whether a patient will respond to fluid therapy (e.g., a blood or fluid infusion) with an improvement in clinical condition, such as an increase in stroke volume and cardiac output. Accordingly, accurate assessments of intravascular volume may assist a clinician in determining whether a patient will be responsive to fluid therapy.
To this end, indicators such as the systolic blood pressure variation, pulse pressure variation, or stroke volume variation may be used to estimate intravascular volume and determine whether a patient is likely to be fluid responsive. However, these measurements tend to be invasive. For example, to obtain an accurate pulse pressure waveform from which the intravascular volume can be determined, a physician may insert an invasive arterial line.